Wow,that sounds very familiar including the swing app part! Except in my case data came from database and code used StringBuffers leading to massive amounts of

Wow,that sounds very familiar including the swing app part! Except in my case data came from database and code used StringBuffers leading to massive amounts of duplication. I had to build a COW wrapper and profile the app to find that 95% of the data was only ever read in normal use cases! Thankfully Java tooling is fairly mature - things like MAT and OQL were of great use in finding the memory hogs and leaks.